The present invention relates to devices for administering, injecting, infusing, delivering or dispensing a substance, and to methods of making and using such devices. More particularly, it relates to a device for administering a fluid or liquid product or substance, e.g. fluid medicaments, pharmaceuticals or cosmetics. More particularly, it relates to a device for administering a fluid product that is to be mixed in a two-chamber carpule (which also may be thought of and/or referred to as an ampoule, container, or the like) before use.
In the treatment of various diseases, e.g. diabetes, and in cases of impaired growth, injection devices or appliances, which may be called injections pens or simply pens, are used to inject a medicament in the form of a fluid product into the body tissue. Such pens can also be used for other pharmaceutical or cosmetic purposes. Typically, a pen comprises a housing, an administering mechanism accommodated at least partially in the housing, and a receptacle for receiving the fluid product, e.g. a carpule holder, which receives a carpule and which is supported by or attached to the housing to connect the carpule to the administering mechanism. Generally, the administering mechanism is composed of a mechanism that is able to drive or move a stopper in the carpule. Generally, at the end of the carpule holder and directed away from the mechanism, an injection needle unit is fitted which forms a fluid connection to the fluid product in the carpule. Typically, an injection pen comprises a trigger button, the actuation of which activates the administering mechanism, such that the medicament is ejected from the carpule through the injection needle. In the prior art, it is known to block or lock the trigger button or to cover it, or in some other way to safeguard against accidental triggering. The blocking or safety feature is overridden or released just before use of the injection pen to be able to carry out an injection.
Two-chamber carpules are often used in practice, these being provided, for example, for administration of hormone preparations. The two-chamber carpules have a first chamber with a lyophilized active substance, and a second chamber with a solvent. The active substance is dissolved in the solvent just before administration, by the solvent being conveyed into the chamber containing the active substance. These two-chamber carpules have two stoppers, which separate the two chambers from each other. During the mixing of the active substance, the two stoppers are moved inside the carpule in such a way that the solvent can run through a bypass into the chamber containing the active substance. Especially when using two-chamber carpules of this kind in an injection pen, it is important to ensure that no accidental or premature administration is initiated, since in such cases the medicament may not have been completely mixed.